Lolliguncula argus is a squid species endemic to the Tropical Eastern Pacific and caught incidentally by the artisanal fishery around Puerto Angel, Oaxaca (Mexico). Due to the low abundance of Argus brief squid, basic aspects of the species’ reproductive biology have not been adequately studied. Therefore, in this study, we assess size at maturity (L50), gonad maturation, ovarian development and spawning pattern by means of both histological and oocyte size–frequency analyses. Our results are based on 581 squid specimens: 534 females (11.9–82.4 mm dorsal mantle length, DML) and 47 males (16.0–68.2 mm DML) caught by artisanal fishery from May 2017 to April 2018. The L50 was 58.0 mm DML for females and 55.4 mm DML for males. The ovulation pattern in L. argus is asynchronous, with multiple-batch spawning in a relatively short period of time (intermittent spawning). Lolliguncula argus breed in the coastal waters off Puerto Angel, in the western margin of the Gulf of Tehuantepec, and exhibit gregarious behaviour during spawning events, which is associated with the regional oceanographic conditions. Based on these results, we determine that the opportunistic reproductive strategy of L. argus occurs in response to suitable regional environmental conditions.

Identifying species and updating marine biodiversity is fundamental to understanding the evolution of ecosystems and adopting appropriate management strategies. These ecosystems are threatened by climate change causing species mobility, mortality, etc. An important zoological group in the marine ecosystem, octocoral gorgonians have a wide geographic and bathymetric distribution. However, the knowledge of their presence on the Atlantic West African coasts remains limited. Herein, we note the accurate geographic distribution of two species, Leptogorgia dakarensis (Stiasny, 1936) and Eunicella racemosa (Milne Edwards & Haime, 1857), reporting their northern distributional limits. The gaps in the previous knowledge hypothesis of the oceanic warming effects explaining the northward mobility of these species are discussed here.

Marine megafauna occurrence was recorded in the deep-sea region bordering the abyssal plain ~400 km north-west of Luanda, Angola. The survey took place during an Environmental Baseline Study (EBS), prior to drilling exploration activities, with the goal of characterizing the habitat and biodiversity of the region. Offshore shipboard surveys were conducted during September 2018 in water depths ranging from 2350–3850 m. We recorded daytime sightings of marine mammals and sea turtles and at night made audio recordings using passive acoustic monitoring (PAM) methods focused on capturing the sounds of vocalizing marine mammals. A variety of species were visually detected, including the humpback whale (Megaptera novaeangliae), sperm whale (Physeter macrocephalus), common dolphin (Delphinus spp.), striped dolphin (Stenella coeruleoalba), Atlantic spotted dolphin (S. frontalis), and olive ridley turtle (Lepidochelys olivacea). Acoustic click bouts similar to those made by several odontocete species, possibly including beaked whales, were recorded within the 25–48 kHz range. The humpback whale was the most frequently sighted species, accounting for 56% of mammal sightings, indicating a potential far offshore migratory habitat in this region. Most notably, right whales (probable Eubalaena australis) were visually observed. This is the first confirmed record of right whales in Angolan waters since the early 1900s. As development expands in this offshore region, these data can usefully inform future monitoring and mitigation strategies focused on minimizing impacts to wildlife.

The species composition and distribution of marine invertebrates varies greatly in different bathymetric regions. Nevertheless, the process of exchange between faunas of different depths has occurred repeatedly throughout the evolution of marine biodiversity. In high latitudes, this process should occur most actively due to absence of strong temperature stratification. The presence of physiological adaptations that allow northern shallow-water organisms to live at greater depth has been demonstrated in a series of experiments. However, known cases of recent colonization by species confined to a highly productive shallow-water zone in unusually deeper Arctic habitats are almost absent. The present study describes finding of population of the gastropod Onoba aculeus (Gould, 1841) in two samples from the lower continental shelf of the Arctic Ocean. Onoba aculeus is a shallow-water amphiatlantic species widely distributed in the temperate regions. The finding reported here is at the same time, the northernmost, easternmost, and most remote from the coast location. We assume that the detection of molluscs indicates the presence of an abundant isolated population in the region.

Studies on benthic foraminifera were conducted in the mangrove forests of Teluk Tempoyak, Pulau Betong and Kuala Sungai Pinang, Penang Island, Peninsular Malaysia to examine species composition and distribution patterns in different intertidal zones. Twenty-eight live benthic foraminiferal species were successfully identified at the study locations, predominantly species with agglutinated tests. Assemblages in Pulau Betong and Teluk Tempoyak were dominated by similar species such as Ammonia aoteana, Elphidium hispidulum, Elphidium neosimplex and Trochammina inflata, while Kuala Sungai Pinang comprises a high number of Trochammina inflata and Arenoparrella mexicana. Three species, Aubignyna perlucida, Elphidium neosimplex and Elphidium sandiegoense, were recorded for the first time in Malaysian mangrove forests. Principal component analysis showed that sediment type and organic matter content were the dominant parameters that explained the variation of environmental gradient. Canonical correspondence analysis of these parameters with benthic foraminiferal species indicated that sand particles influenced distribution of the hyaline tests. Species with agglutinated tests were abundant in sediment with rich organic matter in combination with high silt and clay content. Species with hyaline tests dominated lower intertidal zones, while those with agglutinated tests inhabited the area from the middle to upper intertidal zones. This distribution pattern of benthic foraminiferal species mirrored patterns found at other local and global mangrove locations.

The Chilean torpedo Tetronarce tremens is recorded for the first time in the Mexican Pacific. A single male specimen was captured by artisanal fishermen using a bottom-set gillnet off San Agustinillo, Oaxaca. The specimen identification was based on morphology and confirmed by DNA barcoding of the cytochrome oxidase subunit I gene and its comparison with sequences available in online repositories. A phylogenetic analysis of Tetronarce resulted in the clustering of three species that inhabit the Pacific Ocean: Tetronarce tremens, Tetronarce californica and Tetronarce tokionis. This study provides the northernmost record of Tetronarce tremens in the Eastern Pacific Ocean, an atypical sighting beyond its native distribution range in tropical and temperate waters off South America.

A new record of the diogenid hermit crab Dardanus callichela Cook 1989 is described from the Visayan Sea, Central Philippines. Four specimens of D. callichela were caught in fish traps deployed at depths of about 30–40 m adjacent to islands to the north (Nagarao Island, Masbate) and south (Baliguian Island, Iloilo) of the Visayan Sea. The morphological description and colour photographs are provided. Partial sequences of the cytochrome oxidase subunit I (COI) are provided for two specimens and deposited in GenBank. This new record brings the total number of known Dardanus in the Philippines to 16 species.

The Red Sea is a largely homogeneous water column beyond the top 300 m, unique in exhibiting warm bottom water (~21.5 °C) at depths down to ~2900 m. The unusual conditions coupled with barriers to colonization by primary deep-sea species has resulted in an impoverished but distinct deep fauna. This study presents a rare investigation of the deep Red Sea. The bigeye hound shark Iago omanensis is a known deep-sea shark in the Red Sea. However, its full depth distribution has never been conclusively studied. Here, we confirm with videographic evidence the presence of I. omanensis at depths to 2522 m in the Red Sea, along with observations of other deep-sea species. Iago omanensis was the only species of scavenging fish observed and only in moderate numbers. The additional six species were mostly crustacea in low abundance. The lack of scavenging species present in the deep Red Sea is likely explained by the low productivity of the overlying surface waters and unusually warm water temperature resulting in low energetic input but high metabolic demands in deep communities.

The first record of the parasite Alebion carchariae in the waters of Ascension Island collected from Galapagos sharks, Carcharhinus galapagensis (Carcharhinidae), is described. No previous record of this parasite exists for Ascension Island, nor have Galapagos sharks previously been listed as a host. Specimens of A. carchariae were identified using morphological techniques and DNA barcoding of the cytochrome c oxidase I subunit (COI) gene. This study provides the first COI barcodes for this species and a brief review of known hosts. We recommend further research to understand the life cycle of this parasite, its plasticity in terms of host/habitat selection, and to determine the implications of its presence on the hosts it inhabits.

Limpets (Patella spp.) are marine gastropods that inhabit rocky shores along the coasts of Europe, the Mediterranean, Macaronesia and the north-west coast of Africa. Being considered key species, limpets have an important role regulating algal assemblages in coastal communities. The goal of this work was to evaluate the influence of sea temperature on the respiration rate of four limpet species occurring in mainland Portugal, in line with predictions from the metabolic theory of ecology. The individuals were collected from rocky shores in Portugal and exposed to sea temperatures ranging from 6–28°C for respiration rate assessments. Following the estimation of the relationship between oxygen consumption and temperature the activation energy was calculated. In parallel, low and high thermal thresholds were determined for three of the species. The results indicated that P. ulyssiponensis oxygen consumption increased linearly with sea temperature and the remaining species presented the same tendency. The values of activation energy ranged between 0.33–0.76 eV. For P. ulyssiponensis, the highest activation energy indicated that this species is more sensitive to temperature variations while for the tested temperatures it presented a higher thermal tolerance limit than the other species. Such findings indicate that P. ulyssiponensis is the most susceptible of these species to climate change, in line with the tolerance–plasticity trade-off hypothesis. This work provides a good starting point for understanding the effect of sea temperature on oxygen consumption in Patella spp. and for comprehending sensitivity of limpets to temperature increases under future climate change scenarios.

Deployment of artificial wreck reefs (AWRs) near natural reefs can influence fish assemblages on both reefs. Here, we assessed fish attitudes (abundances, biomass and species richness) according to different level complexity areas of wrecks, feeding guilds of fish and body size of fish of two identical AWRs deployed at the same depth (36.6 m) and different distances from natural reefs. Scuba divers used visual census method to sample fish communities at wrecks for two years. An average of 2346 individuals per dive belonging to 52 species were observed on wrecks combined. Both mean fish abundance and mean biomass did not differ significantly between wrecks. Mean species richness was significantly greater at 9 Eylül than Alaybey. Planktivore was the most abundant feeding guild on wrecks, and its abundance statistically differed between AWRs. The comparisons of fish assemblages at the different level complexity areas of the wrecks show differences, the highest mean abundances were recorded at the areas of low complexity of the wrecks. The results of this study show that although deploying artificial wreck reefs near to natural rocky reefs catalyses fish colonization, it does not present an exact influence on the fish communities of AWRs. We have not known yet how creating an artificial wreck reef affects fish community of natural reefs. With giving extra importance to the choice of deployment area, AWR applications may transform to win-win projects for both the marine environment and recreational users, such as divers and anglers.

The annelid mitochondrial genomes (mitogenomes) have been well documented, and phylogenetic analyses based on the mitogenomes provide insightful implications for annelid evolution. However, the mitogenomes of some families remain unknown. Herein, we determined the complete mitogenome of the lugworm Abarenicola claparedi oceanica (15,524 bp), representing the first mitogenome from the family Arenicolidae. The gene order of this species is the same as the various lineages in Sedentaria. The maximum likelihood phylogenetic analyses were performed based on six different datasets, including 43 ingroups (oligochaetes, hirudineans, echiurans and closely related polychaetes) and two outgroups (Siboglinidae), namely, aligned and trimmed datasets consisting of the nucleotide sequences of protein-coding genes (PCGs) and rRNAs, and amino acid sequences of PCGs. Phylogenetic analyses based on the nucleotide sequences yielded trees with better support values than those based on the amino acid sequences. Arenicolidae is clustered with Maldanidae in all analyses. Analyses based on nucleotide sequences confirm the monophyly of Terebellidae, which was paraphyletic in recent mitogenomic phylogenetic studies. We also performed the phylogenetic analysis based on the RY-coding of the nucleotide sequences of PCGs only to yield phylogeny with generally low support values. Additional mitogenome sequences of related ingroup species would be needed to comprehensively understand the phylogenetic relationship, which was not present in this study.

Kelp forests are regarded as important nursery and foraging habitats for commercially important species of finfish and shellfish despite an absence of fishery-independent data in many regions. Here, we conducted targeted surveys at 12 subtidal reefs, distributed across 9° of latitude in the UK, using three complementary techniques (Underwater Visual Census (UVC), Baited Remote Underwater Video (BRUV) and deployment of prawn pots) to quantify the abundance of crustaceans within kelp forests. Commercially important species were recorded at all sites; Cancer pagurus (brown/edible crab) and Necora puber (velvet swimming crab) were the most abundant and commonly observed, although Maja brachydactyla (spider crab), Homarus gammarus (European lobster) and Palaemon serratus (common prawn) were also recorded. The abundance of some species exhibited pronounced regional variability, with higher abundances of C. pagurus within northern regions and, conversely, higher abundances of M. brachydactyla and P. serratus within southern regions. Each sampling technique yielded similar spatial patterns for the most abundant species but had varying sensitivity to some species. Most individuals observed were juvenile or sub-adults, suggesting kelp forests serve as important nursery grounds for commercially and ecologically important crustaceans. Further monitoring efforts, conducted across greater spatiotemporal scales and in different habitat types, are needed to provide a robust baseline against which to detect changes and to inform management and conservation actions.

Ficopomatus Southern, 1921 is a serpulid genus currently composed of six species, two of which (F. enigmaticus and F. miamiensis) are reef-builders. The former has invaded subtropical and warm-temperate estuaries worldwide, causing environmental and economic harm. In this study, Ficopomatus miamiensis and F. uschakovi are reported from brackish-water coastal localities in both Atlantic and Pacific sides of Mexico, including a Biosphere Reserve, estuaries, as well as shrimp and oyster farms. Ficopomatus miamiensis is reported from Veracruz (southern Gulf of Mexico, Mexico territory) and Sinaloa (southern Gulf of California). Ficopomatus uschakovi is reported for the first time in the southern Gulf of Mexico (Mexico territory) and repeatedly recorded in Chiapas (southern Mexican Pacific). There are no phenotypic differences between specimens of F. miamiensis from both coasts of Mexico. Comparison of mitochondrial cytochrome b (Cytb) DNA sequences further support the notion that F. miamiensis from the type locality (Florida) and Atlantic coasts of Mexico is also found along the Pacific coast of Mexico. Morphological variability within specimens of F. uschakovi from a single locality (either Laguna del Ostión or La Encrucijada) in Mexico suggest potential presence of multiple cryptic species. Molecular genetics studies are needed to confirm the taxonomic and invasive status of F. uschakovi.

A new location record for the night shark, Carcharhinus signatus, is reported for Puerto Rico. DNA barcoding was used to confirm the photo identification of a shark captured incidentally by a small-scale commercial fisher. The adult female night shark was recovered from a depth of 330 m entangled in hook and line gear used in the deep-water snapper and grouper fishery. This record is the first confirmed sighting for Puerto Rico, increasing the shark species reported for the island and supporting its range up to the Mona Passage in the eastern Caribbean Sea.

The paper describes the first report of Kandelia candel (Rhizophoraceae), a rare mangrove from Bhavanapadu, a coastal village in Srikakulam district in Andhra Pradesh, India. This species is relatively less abundant along the east coast of India. During our study covering all the 41 mangrove patches in the state of Andhra Pradesh, 16 mangrove species were observed throughout the state and the Kandelia candel was seen only in Bhavanapadu (patch 2). The plant sighted was identified using taxonomic keys and confirmed using DNA barcoding. The identified specimen is deposited in the museum repository at ICAR-Central Marine Fisheries Research Institute (CMFRI), Kochi (accession no. MB.1.1.1.1) and its gene sequence is deposited in National Center for Biotechnological Information (NCBI) (accession no. MH243746). Patch 2 where K. candel was observed is separated away from the other clusters in the principal component one, with the patch showing an average dissimilarity of about 71.79% from the other patches. K. candel is a mangrove highly sensitive to changes in salinity. The presence of a lone member of a rare species in the state at the sampling location raises questions on its endurance in the region. The study underlines the relevance of monitoring the mangroves and advocate adequate conservation measures for proper protection, proliferation and management of this globally dwindling resource.

Otoliths are an excellent tool in studies on ecological connectivity of fish species populations. Opsanus beta is an invasive species introduced on the Brazilian coast, but not native from the Gulf of Mexico. The present study aimed to compare the otolith contours of specimens collected in Mexico (Celestún, CEL) and in two Brazilian estuaries (Santos Bay, STB, and Paranaguá Estuarine Complex, PEC). In the laboratory, 99 otoliths were extracted, photographed and compared using wavelet analysis. The otolith contours varied between sites (39 from CEL, 26 from STB and 34 from PEC). The linear discriminant analysis correctly reclassified 87.9% of otoliths by sites, with the best reclassifications in the CEL (97.36%), followed by PEC (88.23%) and SBT (73.07%). MANOVA showed significant differences in otolith contours between sites (F = 5.37; P < 0.005). The otolith contour from CEL was significantly different from those from the PEC and SBT. However, the otolith contour of the two Brazilian estuaries did not significantly differ among them (MANOVA, P > 0.005). Our results indicate O. beta populations on the Brazilian coast are connected, and probably isolated from the Mexican population.